Help me figure out what’s going on with my Lab

I have a 14 month old black lab. I don’t know what’s going on with him and need some help. Wednesday was the last time he ate his regular food, but he got sick several time hours later. It wasn’t recent, it was like later in the afternoon and he got sick two or three times. Well ever since then he turns his nose up at everything I’ve tried (chicken broth he ate a little bit of that, white rice and boiled chicken he turns his nose up at). I got him to eat a little plain Greek low-fat yogurt thinking he had digestion issues. Well he threw that up hours later. He doesn’t get sick when he drinks water though. He wasn’t playful or his normal self Wednesday or Thursday morning but Thursday afternoon he was acting like his old self. This morning he was back acting like he wasn’t feeling good again but then tbjs afternoon he was kinda running around in the yard but not 100mph with his hair on fire like his usually self. I also notice when he sleeps he’s shaking but not constantly doing it. I’ve felt around his stomach to see if he had gut pain but he seems fine and lets me do it. I called the vet but they can’t see me until Monday morning. Please help.